Resist the urge to high-five everyone in the cubicles next to you. Your stock may have just strapped on a rocket pack and taken off for the moon, but smart investors won't celebrate until they know that upward leap was justified. Without a fundamental basis for the bounce, these stocks can quickly make the return trip down.

Is now the time to lock in profits, or is this just the first step toward even higher valuations down the road? Let's examine several stocks that just hit the afterburners, and see whether they're truly headed into orbit.

Stock

CAPS Rating (out of 5)

Friday's Change

Fuqi International (Nasdaq: FUQI)

****

28.5%

Gushan Environmental Energy (NYSE: GU)

****

25.6%

MGM Resorts (NYSE: MGM)

**

15.8%

On a day when the market crossed what some say is the psychologically important 11,000 threshold, even a high-flying blue chip can look like a volatile penny stock.

The devil's in the details
No, really, that's why Fuqi International soared? Because its new accountant didn't have any adverse opinions on its financial statements -- well, the ones it filed anyway? The new accountant simply bought the old accountant, and Fuqi still hasn't filed any new financial statements with the SEC in almost a year.

Concerns about Chinese small-cap stocks are mounting daily. We're supposed to believe that business is conducted "differently" over there? The numbers they're reporting to the local securities regulators markedly contrast with those reported to the SEC -- China Sky One Medical (Nasdaq: CSKI), for example, reported results to China's SAIC that were significantly lower than what was reported to the SEC.

In effect, all Fuqi really said was its accountants got bought by someone else. There was nothing new here. And certainly nothing worth a $175 million jump in its market valuation.

Making it to the big time
Gushan Envrionmental Energy also soared on Friday, and while the $5 million stock buyback program it announced could portend positive developments, it hardly seems worth the euphoria investors apparently felt. They're not always worth the hype that surrounds them.

For one, a company that announces a buyback doesn't have to follow through; there's no requirement that it actually do so. Some companies like Microsoft are also starting to taking on massive amounts of debt to fund buybacks, though Gushan isn't one of those. And many times, executive compensation is based on EPS growth, which is easily manipulated by reducing share counts. While Gushan's plan could reduce its shares outstanding by nearly 8% based on the price of the stock when the program was announced, that's already been reduced to a potential 6% reduction because of the shares' jump in value.

Gushan's shares are up about 33% over the past month, and with 97% of the CAPS members rating it to outperform the broad market averages, it appears that many Fools believe it still has the energy to continue putting up market-beating numbers. Add Gushan to your My Watchlist page, and have all the Foolish news and analysis about this stock is aggregated there for you.

Sunny days are here again
Las Vegas is back, baby! MGM Resorts, Wynn Resorts (Nasdaq: WYNN), and even Boyd Gaming (NYSE: BYD) soared on Friday as the Nevada Gaming Control Board reported gambling revenues in Sin City soared 21% in August. Statewide, gaming revenues are up almost 12%.

It's natural then that MGM, as one of the top Las Vegas casino operators, would benefit from the report. MGM also says it's looking at a "very solid" October too. Maybe a little more surprising is that Las Vegas Sands (NYSE: LVS) also rose, since 70% of trailing revenues came from the Chinese gambling oasis of Macau.

It was just last month that CAPS member bigtim820 said to look for a recovery in Las Vegas as a sign of a broader recovery in the economy:

The Vegas comeback will be one of the first indications of the economy rebounding, should see a nice rise as the recovery takes place.

You can double down on MGM's recovery on the MGM Resorts CAPS page and offer your own opinion on whether a bet here will come up snake eyes.

Going into orbit
Just because your stock has taken to the stratosphere doesn't mean it won't lose altitude. Markets are known for overreacting. A closer look at what's happened to your stock can give you an edge over other investors who merely follow the market's lead.

That's why it pays to start your own research on these stocks on Motley Fool CAPS, where you can read a company's financial reports, scrutinize key data and charts, and examine the comments your fellow investors have made, all from the stock's CAPS page. Then you can decide for yourself whether your stock's headed for reentry, or off to infinity and beyond.

Microsoft is a Motley Fool Inside Value recommendation. Motley Fool Options has recommended a diagonal call position on Microsoft. The Fool owns shares of Microsoft. Try any of our Foolish newsletter services free for 30 days.

True to its name, The Motley Fool is made up of a motley assortment of writers and analysts, each with a unique perspective; sometimes we agree, sometimes we disagree, but we all believe in the power of learning from each other through our Foolish community. The Motley Fool has a disclosure policy.

Fool contributor Rich Duprey currently does not own any stocks as you can see here.